Slitting is the dividing of a single, wide strip of metal into narrower strips or slits (also called mults or strands). Some products made from slit metal stock include cans, razor blades, Venetian blinds, office furniture, automobile parts, electrical equipment, appliances, aerospace parts, medical equipment, building materials, jewelry and blanks for minting coins. Slitting is also applied to nonmetallic materials including paper, plastic, film and fiber.
Although metal slitting machines may vary in size from so-called "tabletop" slitters with small motors (used for foil to light gauge material) to those using motors of several hundred horsepower and requiring a building hundreds of feet in length, all slitting machines require essentially the same type of tooling, and vary only in the size, quantity and customization of the end use. A comprehensive review of metal slitting machinery and a discussion of many of the system parameters relevant to such machinery may be found in Rogers, J. W. and Millan, W. H., Coil Slitting, Pergamon Press (1972), the disclosure of which is incorporated herein by reference.
In general, all slitting machines have three major components: (1) a means to get the metal to the slitter--for coil slitters it is an uncoiler (also referred to as an unwinder or payoff reel); (2) a slitter head--for holding the rotary knives and associated tooling (such as spacers, stripper rings etc.) and (3) a recoiler (also referred to as a rewinder or take-up reel)--for rewinding the mults (strands).
In view of the increasingly precise mult width specifications required of metal providers, a design tool for assisting operators of slitting machinery to more accurately adjust mult width to account for slit width variation became very desirable. Accordingly, a design tool was developed by Asko, Inc. of West Homestead, Pennsylvania, that assists an operator to arrive at an estimate of slit width variation and thereby an estimate of the adjustment required of slitter knife position to achieve a desired mult width. This design tool is the subject of U.S. Pat. No. 5,574,890, herein incorporated by reference. Generally, this design tool provided an apparatus for providing an estimation of slit widths for providing an estimation of slit width variation with substantially greater accuracy as was then achievable in metal slitting.
Over the years, it also has been recognized that the edges of slit metal can exhibit a wide variety of configurations, some less favorable than others. Furthermore, it has often been recognized, at a qualitative level, that certain types of slitting parameters, as defined, e.g., by the material being slit, the number and configuration of knives being used, and other factors, can lend a reasonable prediction of the edge defects or conditions that might be encountered. However, because of the subjectivity of such a determination, and because the boundary parameters for delineating the subjective types of edge conditions from one another are difficult to determine qualitatively by an operator, the result has still been a great deal of lost slitting runs. Particularly, a significant quantity of waste material must usually be processed in order to assess the possibly defective edge conditions that might justify the types of adjustments needed to eradicate the defective edge conditions and correct the parameters that bring them about. The same holds true, in fact, in the context of assessing quantitative strip edge conditions (e.g. burr height, shear angle, slit-to-shear ratio, etc.). Accordingly, a need has been recognized in conjunction with providing a predictive analysis of the likelihood that a given slitting run will result in defective edge conditions, and if so, what the edge conditions might actually be.